1 # This file is part of NIT (http://www.nitlanguage.org).
3 # Licensed under the Apache License, Version 2.0 (the "License");
4 # you may not use this file except in compliance with the License.
5 # You may obtain a copy of the License at
7 # http://www.apache.org/licenses/LICENSE-2.0
9 # Unless required by applicable law or agreed to in writing, software
10 # distributed under the License is distributed on an "AS IS" BASIS,
11 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 # See the License for the specific language governing permissions and
13 # limitations under the License.
15 # Introduces a minimal ThreadPool implementation using Tasks
18 intrude import pthreads
19 import concurrent_collections
21 # A simple ThreadPool implemented with an array
23 private var queue
= new ConcurrentList[Task]
24 private var mutex
= new Mutex
25 private var cond
= new NativePthreadCond
26 private var threads
= new Array[PoolThread]
28 # Number of threads used, can only grow after the first call to `execute`
29 var nb_threads
= 5 is optional
, writable
31 private fun create_threads
do
32 while threads
.length
< nb_threads
do
33 var t
= new PoolThread(queue
, mutex
, cond
)
39 # Adds a Task into the queue
40 fun execute
(task
: Task) do
46 # Join all threads, waiting for all tasks to be completed
49 for t
in threads
do t
.join
56 # A Thread running in a threadpool
57 private class PoolThread
60 var queue
: ConcurrentList[Task]
62 var cond
: NativePthreadCond
68 if queue
.is_empty
then cond
.wait
(mutex
.native
.as(not null))
69 if not queue
.is_empty
then
82 # Additional work executed after `main` from a `ThreadPool`
83 private fun after_main
do end
86 # A Task which is joinable, meaning it can return a value and if the value is not set yet, it blocks the execution
93 private var mutex
= new Mutex
94 private var cond
: nullable NativePthreadCond = null
96 # Return immediatly if the task terminated, or block waiting for `self` to terminate
100 var cond
= new NativePthreadCond
102 cond
.wait
(mutex
.native
.as(not null))
107 redef fun after_main
do
108 # TODO move this at the end of main so all `JoinTask` can be joined
109 # no matter what calls `main`.
114 if tcond
!= null then tcond
.signal